Photographic developer and process of development



Patented Mar. 12, 1940 Q UN T D TATES PATENT ,oFFice;g1 j 1 l.

. i it i v f 2492391 i h f PHOTOGRAPHICDEVELOPERAND PROCESS OF DEVELOPMENT i Helmut Borst, Berlin-Kopenick; }erman y No Drawing. Application January 8, 1938; Serial No. 184,037. In Germany December 21; 1936 f 15 claims.- (01.955881,

This invention relates to improvements in voperates up to 10 minutes unobjectionably withphotographic developers and processes of deout fogging, whereas a corresponding developer *velopment; 1 withthe addition of collidine after a time of de-' For the production of the pleasant blue-black velopment of 10 minutes produces considerable 5 shades of developed silver inphotographic emulfogging, which moreover is produce'd'before the 6 sions, a series of blue-black developing sub end of that period. A i 1 stances is known. These substances have, howi In the case of 2.4.6-trimeth'ylpyridine there is ever, certain disadvantages. Thus, .for examinaddition thedisadvantage that this compound pie, nitrobenzimidazole has the great disadvanis liquid andisj-not at all'suitable for the manul0 tage of gradually decomposingin the developer facture' ofrcomm'ercial developers on this ac- 10 and in addition of i considerably retarding -decount. On comparingthe specified chlorinated velopment. Benzotriazole which is likewise frecompound onthe' .other 'handwiththe known quently employed has the unpleasant property nitrobenzimidazole it must beremarked thatby of decomposing very rapidly in the developer meansofthe'chlorinated compound the time of v so thattherefore in use the blue-black developdevelopment is not prolonged and that accord l 1 ing effect of the developer very rapidly deteriingly, nolextension of the time of exposure is 5 crates. A disadvantageous characteristic of all necessa'ry..'This circumstance is tobeconsidered p hitherto known blue-black developing substances as a particular advantage, since in practice it is H further consists in that they have a retarding necessary to'work as fast as possible. In addieffect on the development. In addition these tion it is to be observed that with the applicam- V substances are very sensitive to oxidising and tion of various developers fo t production of p v reducing agents such as cannot be avoided in various tone eiiects it is not of advantage hen" the development. a the times of development or exposure must be In accordance with the present invention all varied from those-with a normal developen these disadvantages are avoided and in addition Th following examples illustrate the inven- 35 a better blue-black tone is produced. ti n,

x Examples A developeraccording to the-invention has'the following composition:

In the process of thisinvention the exposed photographic layer is treated before or during development with a halogen-substituted amino pyridine. Developers according to the invention 30 in solid orliquid form contain the specified sub- Monomethyl-p-aminophenol hydrochloa stance. rid g 2 As particularly suitable substances may be Hydroquinoneuu j 6 mentioned the salts of the halogen-substituted Anhydrous sodium sulphite g 30 2-aminopyr idines, for example 5-iodo-2-amino- Anhydrous sodium carbonate g 30 a pyridine, 5-bromo-2-aminopyridine, 5-chloro-2- Potassium bromide 1 ..g L 0.7 aminopyridine, 5-chloro-2-acetylaminopyridine, Water ccf 1000 354mm?z"ammpyridine and (1) Addition of 0.1 gbor 3.5-dichloro-2-aminopyridine hydrochloride tothis developer base.

40 Such an addition has a series of advantages, in This developer gives on development for the 0 against srfiail szzzzsrts 55 time e known blue-black developers, possibility of easily contammg 3 gg 'i i adjusting the blue shade to any desired strength 9 ed bn ant p c mes w c n par 0 ar the clear blue shade possesses no trace of violet.

avoidance of violet shades, which are produced Moreover no change of the gradation is observed. pamculafly m the shaded portmns of the Image Experiments have further shown that even in' and which lead to loss of the fine gradation of these portions, independence of the composition case of tunes of development of 10 minutes of t developer and others isuch als arg scarcely employed in practice no fog The application of 2.4.6-trimethylpyridine 5 Pro o (collidine) as blue-black addition is indeed Addltwn i Of -a known; this addition has, however, various dis- Pyridine t0 the above developer ase- .advantages, for example in comparison with the i Addition of 0.08 g. of 5-iodo-2-amino- 3.5-dichloro-2-aminopyridine hydrochloride empyridine to the above developer base. v ployed according to the invention. The latter 'Ihese developers not only have no retarding cordance with the principles set forth herein and in the claims annexed hereto.

What I claim is: i 1. In the development of photographic pictures the application to an exposed silverhalide emulsion of an aqueous solution containing a' developing medium for said emulsion and also. i containing a halogen-substituted aminopyridine.

2. Process as claimed in claim 1 in. which a halogen-substituted 2-aminopyridine is employed. 3. Process, as claimed in claim 1 in which a '5-halogen-2-aminopyridine is employed.

4. Process as claimed in claim 1 in which there is employed a compound taken from the class consisting of 5-chloro-, 5-bromo-, and 5- iodosubstituted 2-aminopyridines.

5. Process as claimed in claim- 1 in which l5-chloro-2-acetylaminopyridine is employed.

6. Process as claimed in claim -1 in which a 3.5-dihalogen-2-aminopyridine is employed.

7. Process as claimed in claim 1 in which 3.5- dichloro-Z-aminopyridine isemployed.

a 8. Process as claimed in; claim 1 in which said exposed emulsion is first treated with said halogenated aminopyridine and then subjected to treatment with said developing medium.

9. An article of manufacture comprising a photographic developer containing a silver halide developing agent and a halogen-substituted aminopyridine.

10. An article of manufacture comprising a photographic developer containing a silver halide developing agent and a 5-halogen-2-amino- Pyridine.

11. An article of manufacture comprising a photographic developer containing a silver halide developing agent and 3.5-dichloro-2-aminopyridine.

12. An article of manufacture comprising a photographic developer containing a silver halide developing agent and 3.5-dichloro-2-aminopyridine-hydrochloride.

13. A photographic developer monomethyl-paminophenol hydrochloride, hydroquinone, sodium sulphite, sodium carbonate, potassium bromide and a halogen-substituted aminopyridine.

14. A photographic developer as, claimed in claim ,13 in which there is employed a compound taken from the class consisting of 5-chloro-, S-bromopyridines.

15, A photographic developer as claimed .in claim 13 containing 3,5-dichloro-2-aminopyridine as a halogen-substituted aminopyridine.

' HELMUT BORST.

containing and 5-iodosubstituted 2-amino- 

